1. Field
The present disclosure relates to a moving robot and a control method thereof, and particularly, to a moving robot capable of passing through an obstacle and a control method thereof.
2. Background
In general, robots have been developed for industrial purposes and have been in charge of part of factory automation. Recently, robot-applied fields have further extended to develop medical robots or aerospace robots, and home robots that may be used in general houses have also been made.
A typical example of a home robot is a robot cleaner, which may be a home appliance that cleans by sucking ambient dust or foreign objects, while traveling in a predetermined area. Such a robot cleaner may include a generally rechargeable battery and have an obstacle sensor capable of avoiding an obstacle during traveling so that the robot cleaner may perform cleaning while traveling.
Recently, beyond performing cleaning while robot cleaners are simply autonomously traveling in a cleaning area, research into utilization of robot cleaners in various fields such as healthcare, smart home, remote control, and the like, has been actively conducted. When a robot cleaner performs autonomous traveling in a cleaning area, the robot may meet various obstacles present in the cleaning area, and thus, an algorithm for avoiding such obstacles when performing autonomous traveling and cleaning operation may be required.
However, when a bottom surface of the cleaning area is not even, if all surface portions which are not even are recognized as obstacles, a cleaning range may be reduced, and thus, a recognition reference related to an obstacle may not be set too strictly. Thus, when the robot cleaner passes through a portion of the bottom surface without recognizing an uneven portion of the bottom surface as an obstacle, at least one of a plurality of wheels may not come into contact with the bottom surface, generating idle rotation, making it impossible for the robot cleaner to normally travel.
Also, when at least one of the plurality of wheels of the robot cleaner is completely arrested, the arrested state of the wheel may not be released only by an output from a motor.
Thus, a robot cleaner that solves an idle rotation phenomenon and a complete arrest phenomenon of the wheel that may occur when the robot cleaner passes on bottom surfaces of various conditions and a control method thereof may be required.
A robot cleaner may have various types of driving devices and traveling performance of a robot cleaner may be varied according to types of the driving unit. A robot cleaner may have a main driving wheel connected to a separately operable motor and an auxiliary driving wheel minimizing a frictional contact between a lower surface of a main body and a floor surface (cleaning target surface). The main driving wheel and auxiliary driving wheel of the driving device used in a robot cleaner may have a circular shape.
A case in which a caterpillar having a circular shape is applied to a robot cleaner has been introduced. A robot cleaner having such a caterpillar type driving unit may be suitable for traveling on an uneven floor surface. However, when the robot cleaner employing the caterpillar meets an obstacle as a target to be passed such as a threshold, the robot cleaner may not properly pass through the obstacle and the driving unit may be arrested by the obstacle.
In particular, due to an irregular portion of the floor surface, a rear surface of the robot may be in contact with the floor surface and the driving unit may idly rotate in a floating state. In a robot described in Korean Patent Registration No. 10-1530704, an angle between left and right auxiliary caterpillar modules and left and right main caterpillars may be changed to correspond to a height or a slope of an obstacle to secure a frictional force regarding the obstacle by the left and right auxiliary caterpillars.
However, in the related art robot, it may not be possible to secure a frictional force regarding an obstacle only by the main caterpillar, and an auxiliary caterpillar installed on a side surface of the main caterpillar may be required. Thus, manufacturing cost of the robot to install the auxiliary caterpillar may be increased, and since separate power should be supplied to the auxiliary caterpillar, efficiency of power consumed in the robot may be reduced.
Also, since the auxiliary caterpillar is added, a weight of a main body of the robot may be increased to cause user inconvenience. When a frictional force regarding an obstacle is secured using the auxiliary caterpillar as in the related art robot, a width of the main body of the robot may be excessively increased to make it more difficult for the robot to pass through an obstacle than a robot without such an auxiliary caterpillar.
Also, when the related art robot passes over an obstacle, only power transmitted to the auxiliary caterpillar may be used and idle rotation still may occur in the main caterpillar. The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.